In a cellular communication system, also referred to as a wireless communication system, user equipment, also known as mobile terminals and/or wireless terminals communicate via a Radio Access Network (RAN) to one or more core networks. The user equipment are mobile telephones also known as “cellular” telephones, and laptops with wireless capability, or similar portable, pocket, hand-held, computer-included, or car-mounted mobile devices which communicate voice and/or data via a radio frequency transmission.
The radio access network covers a geographical area which is divided into cell areas, with each cell area being served by a base station, e.g., a Radio Base Station (RBS), which in some networks is referred to as “eNB,” “NodeB,” “eNodeB,” “Base Station Subsystem,” “BSS” or “B node” and which in this document is referred to as a base station. A cell is a geographical area where radio coverage is provided by the base station equipment at a base station site. The base station communicates using an over-the-air interface that operates on radio frequencies with the user equipment within range of the base station.
In some versions of the radio access network, several base stations are typically connected, e.g. by landlines, optical fiber or microwave, to a Radio Network Controller (RNC). The radio network controller, also sometimes termed a Base Station Controller (BSC), supervises and coordinates various activities of the plural base stations connected thereto. The radio network controllers are typically connected to one or more core networks.
The user equipment and the base station can form a Universal Mobile Telecommunications System (UMTS), which is a third generation mobile communication system, and can provide improved mobile communication services based on Wideband Code Division Multiple Access (WCDMA)—high speed packet access (HSPA) technology. At the physical layer, HS-DPCCH is one of the uplink control channels on which the UE transmits to the base station. It consists of two parts. The channel quality indicator (CQI) and the hybrid automatic repeat request (HARQ) signal. A HARQ message, which is an acknowledgement (ACK) or a negative acknowledgement (NACK) or a combination of more than one of them, is transmitted when the UE has something to report about the recently received high speed downlink shared channel (HS-DSCH) data subframes from the base station. If the UE does not receive any frames from the base station, it will not transmit anything. In other words, it will transmit a zero-power message which is referred to as ‘Discontinuous Transmission’ (DTX). The codebook of the HARQ message depends on whether the UE is scheduled in multiple input multiple output (MIMO) mode or not, the number of simultaneous carriers, and similar criteria.